When you would you hire someone on a service like Fiverr.com and assign them an email account?I create an email account for them to use, thereby not having to ask for their contact information. I stay within Fiverr.com’s Terms of Service that way.

When you would respond on behalf of one of your hires. (e.g. training person, key sale, etc.)

Also, anytime you want to easily monitor what someone you have hired to represent you, this is a good tool.